Example or documentation for fixing sampling proportion to 0 before the first sample in BDSKY-serial xmls

[Martin Gunnill]

Dear BEAST2ers

Is there an example xml or documentation for fixing sampling proportion to 0 before the first sample in BDSKY-serial xmls.  

I am trying to add a function to do this to [beast2-xml](https://github.com/acorg/beast2-xml). 

I have been going from an example in a previous post: https://groups.google.com/g/beast-users/c/JW9MGdQzSlc/m/cr85EAzjDAAJ.

So far, I have come produced two xmls, see https://github.com/m-d-grunnill/beast2_fixing_sampling_proportion_to_0.

• fixed_at_0.xml: causes BEAST to crash complaining 'Start likelihood: -Infinity after 10 initialisation attempts'. Tried different seeds.
• fixed_at_0.00001.xml: This is the same as fixed_at_0.xml but with the fixed value being 0.00001. This runs but the first sampling proportion is still being altered in the log files.
  

Yours Martin